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Ladder filter and duplexer

a duplexer and ladder filter technology, applied in the field of ladder filters, can solve the problems of difficult to further promote miniaturization, and achieve the effects of enhancing the disposition density of resonators, reducing the dimensions in the propagation direction of elastic waves, and reducing the dimensions of elastic wave propagation

Active Publication Date: 2013-01-03
MURATA MFG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The invention provides a ladder filter with a series arm resonator and a parallel arm resonator on one piezoelectric substrate for miniaturization purposes. Additionally, it provides a duplexer with the ladder filter for achieving miniaturization and a band pass filter.

Problems solved by technology

Accordingly, it has been difficult to further promote miniaturization.

Method used

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  • Ladder filter and duplexer
  • Ladder filter and duplexer
  • Ladder filter and duplexer

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Embodiment Construction

[0035]Hereinafter, the present invention will be clarified by explaining specific preferred embodiments of the present invention with reference to drawings.

[0036]FIGS. 1A and 1B are schematic plan views of a ladder filter according to a preferred embodiment of the present invention.

[0037]In a ladder filter 1, on a piezoelectric substrate 2, a plurality of series arm resonators S1 to S3 and a plurality of parallel arm resonators P1 and P2 are configured.

[0038]The piezoelectric substrate 2 may preferably be formed using piezoelectric single crystal such as LiNbO3 or LiTaO3 or arbitrary piezoelectric ceramics, for example.

[0039]The series arm resonators S1 to S3 and the parallel arm resonators P1 and P2 include surface acoustic wave resonators. In FIG. 1B, the electrode structure of the series arm resonator S1 will be described as a representative of the surface acoustic wave resonators. As illustrated in FIG. 1B, reflectors 4 and 5 are located on both sides in the elastic wave propaga...

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Abstract

A ladder filter including a series arm resonator and a parallel arm resonator disposed on the same common piezoelectric substrate achieves improved miniaturization. The ladder filter includes series arm resonators and parallel arm resonators, which include elastic wave resonators, and are disposed on the same common piezoelectric substrate, at least one parallel arm resonator of the series arm resonators and the parallel arm resonators includes a first resonator and a second resonator electrically connected in parallel to each other, and the first resonator and the second resonator are arranged in parallel or substantially in parallel in a direction perpendicular or substantially perpendicular to an elastic wave propagation direction, on one side outside one series arm resonator of remaining resonators in the elastic wave propagation direction thereof.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a ladder filter including a plurality of elastic wave resonators. In more detail, the present invention relates to a ladder filter including a series arm resonator and a parallel arm resonator, which include elastic wave resonators, located on one piezoelectric substrate, and a duplexer including the ladder filter, defining at least one band pass filter.[0003]2. Description of the Related Art[0004]In the past, ladder filters have been widely used as band pass filters for mobile phones. In addition, in this type of ladder filter, so as to achieve miniaturization, a series arm resonator and a parallel arm resonator are configured using surface acoustic wave resonators.[0005]For example, in Japanese Unexamined Patent Application Publication No. 2000-201052, an example of such a ladder filter is disclosed. FIG. 8 is a plan view schematically illustrating this ladder filter.[0006]In the ladde...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H03H9/72H03H9/64
CPCH03H9/14547H03H9/725H03H9/6463H03H9/6426H03H9/6483
Inventor UESAKA, KENICHI
Owner MURATA MFG CO LTD
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